1. Field of the Invention
The present invention pertains to shielded connector assemblies which are mateable with a shielded plug connector. More particularly, the present invention pertains to shielded receptacle assemblies mountable on a printed circuit board or the like, having an overlying metallic shield with one or more reversely bent fingers for engaging the plug shield as the plug and receptacle are mated.
2. Background of the Invention
Shielded electrical connector systems are enjoying popularity today, due in part to the recent limitations placed on radio frequency emmissions generated by electronic equipment, such as computers and other digital information systems.
One type of shielded connector system is shown in U.S. Pat. No. 4,337,989 which provides a shielding kit for use with a conventional plug and receptacle connector assembly, such as that used as an input/output (I/O) interface for electronic communications equipment. The receptacle, which is mounted on a printed circuit board, includes a dielectric housing having a mating edge and a plug-receiving cavity extending into the housing from the mating edge, an end wall opposite the mating edge, and a plurality of sidewalls joining the end wall to define the plug receiving cavity. Terminals, typically extending from the end wall, are mounted in the receptacle housing for mating contact with corresponding plug terminals. The kit includes a metallic shroud, generally U-shaped in cross-section, which fits over the dielectric receptacle, having board engaging ears for mounting to the same printed circuit board as the receptacle connector. The metallic shroud includes a number of reversely bent cantilever spring fingers located near the top housing wall, and extending into the plug receiving cavity from the mating edge. The cantilever spring fingers mate with the outer metallic shell surrounding the plug member, as the plug is inserted in the receptacle housing. The cantilever spring fingers formed as part of the metallic shroud are typically provided in groups of three or more to engage the mating plug shield at a plurality of contact points. The plurality of spring fingers offers advantages over a single contact finger design in that any warpage or other malformation of the plug shield can be accommodated more readily by a plurality of independently operating spring finger members. Such members are deflected so as to close the reverse bend during mating of the plug and receptacle assemblies.
While the conventional receptacle shown in U.S. Pat. No. 4,337,989 includes a top wall extending to the mating edge, a popular design in use today has omitted the upper housing wall portion to allow freedom of movement of the resilient spring fingers. The upper metallic shroud wall from which the fingers extend is thereby made subject to outward bowing or deflection during mating with a plug connector. In order to overcome outward bowing, and to provide the resilient forces required for proper electrical mating with the plug shield, the metallic shroud is typically formed of metal stock somewhat thicker than would otherwise be required. For example, the metallic shield in widespread use today is formed of a phospor-bronze composition, in thicknesses of approximately 0.020 inches. A thinner shield material would offer cost saving advantages, and would afford greater compliance in conforming to a mating plug configuration, but, as explained above, the shield would be subjected to outward bowing, with an attendant reduction in the contact pressure of the centrally located spring fingers.
The kit referred to above, and particularly the receptacle shield portion thereof, is intended for manual installation by an operator who is otherwise required to provide other assembly operations in the appliance manufacture. However, certain electronic appliances are being produced by automated assembly techniques, and the manufacturers of this equipment realize a cost savings if the connector components provided them can be installed automatically, as by a robotic insertion head, or the like.